T least one electron-withdrawing group and carbon disulfide 1,3-dithiole derivatives from acetylenic compounds substituted with a

ABSTRACT

ACETYLENIC COMPOUNDS R1C$CR2, IN WHICH AT LEAST ONE OF THE R1 AND R2 SUBSTITUENTS IS AN ELECTRON-WITHDRAWING GROUP REACT WITH CARBON DISULFIDE TO GIV E DITHIOL COMPOUNDS OF THREE DIFFERENT FORMULAS, THEIR RATIO DEPENDING ON THE REACTION PARAMETERS. IN THE PRESENCE OF A COREACTANT HX, A DITHIOLE SUBSTITUTED WITH THE X GROUP IN THE 2-POSITION IS FORMED. IN THE PRESENCE OF A CARBOXYLIC ACID OR OF AN ETHYLENIC COMPOUND, ACETYLENIC COMPOUNDS R1C$CR1 REACT WITH CARBON DISULFIDE TO FORM OTHER 2SUBSTITUTED DITHIOLES. THE NOVEL COMPOUNDS OF THIS INVENTION ARE USEFUL IN REMOVING TARNISH FROM SILVERWARE.

United States Patent Olfice 3,758,503 Patented Sept. 11, 1973 3,758,503 1,3-DITHIOLE DERIVATIVES FROM ACETYLENIC COMPOUNDS SUBSTITUTED WITH AT LEAST ONE ELECTRON-WITHDRAWING GROUP AND CARBON DISULFIDE Harris Dale Hartzler, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del. No Drawing. Filed June 17, 1970, Ser. No. 47,111 Int. Cl. C07d 71/00 US. Cl. 260-327 M Claims ABSTRACT OF THE DISCLOSURE Acetylenic compounds R CECR in which at least one of the R and R substituents is an electron-withdrawing group react with carbon disulfide to give dithiole compounds of three difierent formulas, their ratio depending on the reaction parameters. In the presence of a coreactant HX, a dithiole substituted with the X group in the 2-position is formed. In the presence of a carboxylic acid or of an ethylenic compound, acetylenic compounds R CECR react with carbon disulfide to form other 2- substituted dithioles. The novel compounds of this invention are useful in removing tarnish from silverware.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to novel 1,3-dithiole derivatives, which are obtained from carbon disulfide and certain acetylenic compounds, optionally in the presence of selected coreactants.

Prior art 'Krespan and England, J. Org. Chem., 33, 1852 (1968) reported the formation of the compound e= =o OFa-C-S S--CC F,

by a reaction of hexafiuoro-Z-butyne with sulfur and carbon disulfide at 200 C.

Acetylene itself is known to react with carbon disulfide, giving thiophene.

SUMMARY OF THE INVENTION It has now been discovered, according to the present invention, that acetylenic compounds of the formula R CE CH in which R is an electron-withdrawing group, such as carboxyl, alkoxycarbonyl of up to 12 carbon atoms, aryloxycarbonyl of up to 13 carbon atoms (including the carbonyl carbon), lower perfluoroalkyl, arylcarbonyl of up to 13 carbon atoms (including the carbonyl carbon), or the cyano group; and

R is either the same as R or hydrogen, a C -C alkyl, aryl of up to 12 carbon atoms, or alkaryl of up to 12 carbon atoms react with carbon disulfide to give products having the following Formulas 1, 2, and 3, their ratio depending on the reaction conditions.

In the presence of a coreactant HX, the substituted 1,3- dithiole of Formula 4 is formed IU-C-S H l R s X (4) In the above formulas X can be one of the following groups:

where R R R and n are as defined above; and

R4 -o-0om where R is hydrogen, lower alkyl, or aryl of up to twelve carbons;

R is hydrogen, lower alkyl, lower alkanoyl, or aryl of up to twelve carbons;

R is hydrogen, lower alkyl, aryl of up to twelve carbons, or alkaryl of up to twelve carbons; but R and R taken together can be alkylene of from about two to twelve carbons.

Substituted acetylenes of the formula R CECR wherein R has the above-defined meaning, react with carbon disulfide in the presence of a carboxylic acid HZ, in which Z is an aroyloxy group or an alkanoyloxy group of up to 13 carbon atoms, or in the presence of ethyleneic compounds having the formula CH =CHR", in which R is hydrogen, lower alkyl, an alkanoyloxy group of up to 13 carbon atoms, or phenyl. The products obtained in the above reactions can be represented by the following Formula 5 n -c-s 5 where Y, individually, is hydrogen;

Z, individually, is an aroyloxy group or an alkanoyloxy group of up to 13 carbon atoms; or

Y and Z taken together are on, R being defined above.

The products of this invention are useful for removal of tarnish from silverware.

3 DETAILED DESCRIPTION OF THE INVENTION While all the products of the present invention have one or more 1,3-dithiole rings in their molecules, their structures vary with either the starting materials or the reaction parameters. Among the simpler reaction products are those shown by Formulas 4 and 5, above.

Compounds having the general Formula 4 are formed in a reaction of an acetylenic compound R1CECR2 with carbon disulfide and a coreactant HX; R R and X having been defined above. Depending on the nature of X, the coreactant HX can be lower alcohol, a phenol with at least one unsubstituted ortho or para position, an aldehyde or ketone containing at least one tat-hydrogen, benzaldehyde or a derivative thereof, or cinnamaldehyde or a derivative thereof. The term lower alcohol means an aliphatic alcohol having up to five carbon atoms.

Representative HX coreactants include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol (all isomers) amyl alcohol (all isomers), 2-chlorophenol, 4 chlorophenol, 2,6-dichlorophenol, 4-bromophenol, m-cresol, o-cresol, 2,3 dimethylphenol, 3,5-dimethylphenol, 2,4 dimethylphenol, p ethylphenol, pmethoxyphenol, o-ethoxyphenol, p-propoxyphenol, methyl salicylate, ethyl salicylate, methyl p-hydroxybenzoate, butyl m-hydroxybenzoate, resorcinol, hydroquinone, catechol, p-nitrophenol, m-nitrophenol, o-nitrophenol, salicylonitrile, p-hydroxybenzonitrile, 2-hexylphenol, 2- bromophenol, 3-fiuorophenol, 4-iodophenol, 4-chloro-3- fluorophenol, 5-butyl-2-chlorophenol, 3,5-xylenol, 2-isopropyl-S-methylphenol, 2,6-dichlorophenol, m-isopropoxyphenol, and butyl salicylate.

HX can be also benzaldehyde, cinnamaldehyde, propanol, propionaldehyde, valeraldehyde, heptanal, dodecanal, tridecanal, acetone, methyl ethyl ketone, diethyl ketone, butyl ethyl ketone, dihexyl ketone, acetophenone, ethyl phenyl ketone, propyl naphthyl ketone, butyl anthryl ketone, cyclopentanecarboxaldehyde, cyclohexanecarboxaldehyde, cycloheptanecarboxaldehyde, cyclopentanone, cyclohexanone, cycloheptanone, benzophenone, phenyl naphthyl ketone, 2-ethyl-4-methylpentanal, phenylacetaldehyde, 1 (2-naphthyl)-2-butanone, a,a-diphenylacetophenone, 2-methyl-3-hexanone, 2,2-dimethyl-S-heptanone, 8-pentadecanone, 5-methyl-2,4-hexanedione, 7-methyl-2,4- nonanedione, 3 methyl-2,4-pentanedione, 2,6-dimethyl- 3,5 heptanedione, 5,5 dimethyl-2,4-hexanedione, 2-acetonaphthone, 3-phenylacetophenone, 4-methylpropiophenone, 3-ethylacetophenone, 2,4,6-trimethylacetophenone, 4-t-pentylacetophenone, cyclobutanone. p-hydroxybenzophenone, 3 methylcyclopentanone, cyclododecanone, 3- isopropylcyclohexanone, and 3-ethyl-S-methylcyclohexanone.

'HX can also be benzaldehyde, cinnamaldehyde, naphthaldehyde, anthraldehyde, naphthylvinylaldehyde, and anthrylvinylaldehyde; as well as their substituted derivatives in which the substituents can be, for example, chlorine, bromine, iodine, fluorine, methoxyl, ethoxyl, propoxyl, isopropoxyl, pentoxyl, isopentoxyl, methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, pentoxycarbonyl, benzoyl, the nitro group, or the cyano group.

Such substituted aldehydes include, for example, the following compounds: 3,5 dimethylbenzaldehyde, 2- phenylbenzaldehyde, p-(sec-butyl)benzaldehyde, 2,4,6-triethylbenzaldehyde, p-isopropylcinnamaldehyde, o-methylcinnamaldehyde, p-phenylcinnamaldehyde, 2-naphthaleneacrolein, 4-isopropyl-1,6-dimethylnaphthaldehyde, S-nitrol-naphthaldehyde, p-ethoxycinnamaldehyde, m-chlorobenzaldehyde, o-isopentyloxybenzaldehyde, m-cyanobenzaldehyde, p-methoxycarbonylbenzaldehyde, o-nitrobenzaldehyde, and p-benzoylbenzaldehyde.

R can be a lower alkyl, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, and isoamyl; an aryl, such as phenyl, a-naphthyl, fl-naphthyl, or anthryl; or allgaryl, such as O-tolyl, m-tolyl, p-tolyl,

xylyl, duryl, ethylphenyl, a methylnaphthyl, an ethylnaphthyl, or propylphenyl.

R can, in addition, be the same as R which is, among others, methoxycarbonyl, ethoxycarbonyl, phenoxycarbonyl, naphthoxycarbonyl, anthryloxycarbonyl, trifluoromethyl, pentafiuoroethyl, heptafluoropropyl, benzoyl, toluoyl, naphthoyl, or anthranoyl. As stated earlier, R and R can also be carboxyl or the cyano group.

Acetylenic compounds which are suitable as starting materials for the practice of this invention include, among others, the following: hexafluoro 2 butyne, dimethyl acetylene-dicarboxylate, diethyl acetylenedicarboxylate, methyl propiolate, ethyl propiolate, propiolic acid (2- propynoic acid), tetrolic acid (2-butynoic acid), 2-octynoic acid, phenylpropiolic acid, m-tolylpropiolic acid, l-naphthylpropiolic acid, 4 biphenylylpropiolic acid, ethyl tetrolate, butyl phenylpropiolate, phenyl propiolate, 3,3,3 trifluoropropyne, 3,3,4,4,4 pentafluoro-lbutyne, 1,1,1 trifluoro 2 butyne, 1,1,1-trifluorophenylpropyne, 3 butyn 2 one, 1-hexyn-3-one, 4-octyn-3-one, 3-undecyn-2-one, 4 phenyl 3 butyn 2 one, 1-phenyl- 2 hexyn-l-one, 1-pheny1-l-decyn-3-one, 1-naphthyl-2- propyn 1 one, 1 (2,4,6 trimethylphenyl)-3-phenylpropyn 1 one, 1,3-diphenylpropynone, propiolonitrile, 2-heptynenitrile, acetylenedicarboxylic acid, hexyl acetylene-dicarboxylate, phenyl acetylenedicarboxylate, perfluoro 2 heptyne, 3 hexyne-2,5-dione, 5-decyne-4,7- dione, 1,4-diphenyl-2-butyne-1,4-dione, 1,4-bis(3,5-xylyl)- 2 butyne 1,4-dione, 1,4-di-p-tolyl-2-butynedione, and acetylenedicarbonitrile (dicyanoacetylene or butynedinitrile).

Preparation of compounds of Formula 4 does not require exact stoichiometric amounts of the starting mate rials. In practice, excess of both carbon disulfide and the coreactant is preferred. Although a tenfold, or even higher, excess of either one of these two starting materials can be used, it is not practical to exceed the or HX:R CECR molar ratio of 2:1 to 3:1.

The reaction is carried out a temperature of about 45- C. The rate of reaction decreases with decreasing temperatures, and the reaction is quite slow at about 30 C. Temperatures above 150 C. can be used, but it is not advisable to exceed about 200 C. because of thermal instability of the products.

This reaction can be run at either normal pressure or at superatmospheric or subatmospheric pressure. Because of the high volatility of carbon disulfide and of the volatility of certain acetylenic compounds and of the HX coreactants, it is convenient to conduct this process at autogenous pressure in a closed :system. However, the process is not limited to batch operations and can, at sufficiently high pressures and temperatures, be adapted to continuous operations. Under autogenous pressures, within the preferred temperature range, the reaction time varies from several hours to several days.

No solvent need be added to the reaction mixture, but excess carbon disulfide or HX reactant serves at the same time as the reaction solvent. Unsubstituted aliphatic esters, ethers or nitriles also can be used as solvents.

Compounds of Formula 5 can be prepared by contacting an acetylenic compound, RICECRI, and carbon disulfide with a lower alkanoic acid, an arenecarboxylic acid, or alkarenecarboxylic acid of up to 13 carbon atoms. A lower alkanoic acid for the purpose of this invention is an alkanoic acid having no more than six carbon atoms. Typical carboxylic acids which are useful in this process include: formic, acetic, propionic, butyn'c, isobutyric, pentanoic, hexanoic, benzoic, 1- and Z-naphthoic, anthranoic, 0-, m-, and p-toluic, dimethylbenzoic, ethylbenzoic, 8-methyl-1-naphthoic, 2,4,6-triethylbenzoic, 4-pentylbenzoic, trimethylacetic, a-ethylbutyric, and ethylnaphthoic acids.

The reaction product will have the Formula 5, above, in which Y is hydrogen, and Z is the alkanoyloxy or aroyloxy group derived from the starting acid.

Reaction of an acetylenic compound R CECR with carbon disulfide and an ethylenic compound CH -CHR' leads to the product having the Formula 5, in which Y and Z taken together form the group CHR1 The radical R can be, among others, a lower alkyl, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, or pentyl (all isomers). It also can be a lower alkanoyloxy group, such as formoyloxy, acetoxy, propionoxy, butanoyloxy, pentanoyloxy, and various isomers of the last two named radicals. R can also be hydrogen or phenyl. Representative ethylenic compounds include: vinyl butyl ether, vinyl 2-ethylhexyl ether, vinyl 1-isopropyl-2-methylpropyl ether, vinyl acetate, vinyl isobutrate, vinyl heptauoate, propylene, isobutylene, and l-heptene.

The process conditions are similar to those discussed above in connection with compounds of Formula 4, and the effects of process variables are comparable.

Products of Formulas 1, 2, and 3 are made by contacting an acetylenic compound RLCECR2 with carbon disulfide. By varying the conditions, any one of these types can be formed predominantly or exclusively.

The formation of Type 1 can be favored by adding a lower alkanoic acid or a lower haloalkanoic acid to the system as a promoter or catalyst. Such an acid will have a R, (in an aqueous solution, at 25 C.) of less than about five. The lower the pK,,, i.e., the stronger the acid, the higher will be the yield of a product of Formula 1. Haloalkanoic includes monohaloalkanoic and polyhaloalkanoic, including perhaloalkanoic. The preferred halogen substituents, for economic reasons, are fluorine and chlorine. Suitable acids, together with their pK s, include formic acid (3.75), acetic acid (4.76), isovaleric acid (4.77), iodoacetic acid (3.18), a-bromopropionic acid (2.97), difluoroacetic acid (1.24) and trichloroacetic acid (0.92). The pK values of many such acids (or K values, from which pK can easily be calculated) are given, for example, in Handbook of Organic Structural Analysis, Ed Yukawa (Benjamin, 1965), pages 614 11. Also, see the discussion following Example 23, below.

The acid concentration usually is maintained between about 0.1 mole and 1 mole per mol of the acetylenic compound. The catalytic effect of the acid is still perceptible at molar ratios as low as about 0.01:1. Although any large amount of the acid can be used, there is no advantage to exceed the molar ratio of about 3: 1.

In the absence of a carboxylic acid catalyst, compounds of Formulas 2 and 3 are the principal products. Carbon disulfide is usually present in a larger than equimolar amount with the acetylenic compound. A small excess of carbon disulfide favors the formation of a product of Formula 3, while a larger excess (e.g. 5-10 moles of CS for each mole of the acetylenic compound) favors the formation of a product of Formula 2. The effects of temperature, pressure, and reaction time are comparable with those discussed above in connection with compounds having the Formula 4.

This invention is now illustrated by the following representative examples of certain preferred embodiments thereof.

All the experiments described in the examples were carried out in sealed glass or stainless-steel tubes. After the stated period of heating, the tubes were cooled before being opened. All temperatures are in C. In pressure measurements, the term torr is equivalent to millimeters of mercury. In nuclear magnetic measurements (NMR) data, the numbers in brackets refer to relative intensities.

Infrared absorption spectra of liquids were taken on the pure materials; spectra of solids were determined on potassium bromide discs. In the infrared data, the absorption frequencies are in cm.- and terms (s.), (m.) and (w.) correspond to strong, medium and weak absorption. In the ultraviolet absorption data, nm. stands for nanometers and sh. means a shoulder.

EXAMPLE 1 4,5-bis(trifluoromethyl) -2-methoxy-1,3-dithiole (Formula 4; R =R =CF X=OCH CFr-C H A mixture of 15 ml. of carbon disulfide, 15 ml. of methanol, and 16 g. of hexafluoro-Z-butyne was heated at for two days. Distillation of the product gave 5.6 g. (21%) of 4,5-bis(trifiuoromethyl) methoxy-l,3-dith'iole which boiled at 80 at 24 torr, 11 1.4255.

Analysis.Calcd. for C H F OS (percent): C, 26.27; H, 1.49; S, 23.73; F, 42.19. Found (percent): C, 26.64; H, 1.46; S, 23.78; F, 42.26.

P NMR: Singlet at +3138 c.p.s. from trichlorofiuoromethane.

H NMR: Singlets at 6 3.09 [3] and 6 6.43 [1].

IR: Double bond C=C absorption at 1595 cm."

UV: In isooctane, 1 287 (E 3210), 269 (e 3910) and 212 nm. (e 3670).

Mass spectrum M./e. Intensity Assignment 270 4, 320 Parent 251 1,710 P-F 239 224,990 POCH 201 385 P-CFa CF=C=C CF C=C-S+ 143 1,119 CFz-fill (JIM-0+ 1,029 CF CsCS+ 69 2,244 CFfl- EXAMPLE 2 4,5-bis(trifluoromethyl)-2-ethoxy-1,3-dithiole (Formula 4; R =R =CF X=OC H CFaC-S H NMR: Methine CH) [1] singlet at 6 6.42, methylene (CH quartet [2] centered at 6 3.38, and methyl triplet [3] centered at 6 1.03.

IR: Double bond at 1590 cm." and strong, broad C-F absorption.

7 EXAMPLE 3 4-carbomethoxy-Z-methoxy-1,3-dithiole (Formula 4; R =COOCH R =H; X=OCH HO-S H CH3O C O-S OCH;

A mixture of 9 g. of methyl propiolate, 15 ml. of carbon disulfide, and 15 ml. of methanol was heated at 100 for four days. Distillation gave 2.7 g. of 4-carbomethoxy- 21nethoxy-1,3dithiole, B.P. 99 at 0.9 torr, 11 1.5696.

Analysis.Calcd. for C H O S (percent): C, 37.48; H, 4.20; S, 33.36. Found (percent): C, 37.65; H, 4.20; S, 33.28.

H NMR: Methine resonance at 6 7.32 [1] and 6.89 [1] and methoxy resonance at 6 3.67 [3] and 3.07 [3]. IR: 3000 (m.), 1710 (s.), 1550 (s.), 1440 (s.), 1340 (w.), 1280 (s.), 1250 (s.), 1210 (m.), 1190 (m.), 1050 (s.), 950 (m.), 900 (s.), 850 (m.), 830 (m.), 770 (s.), 750 (s.), 730 (s.).

UV: 'In ethanol, A 304 (e 6600) and sh. 230 nm. (e 4050).

EXAMPLE 4 4-carbethoxy-2-methoxy-1,3-dithiole (Formula 4; R =COOC H R =H; X=OCH A mixture of 20 g. of ethyl propiolate, 20 ml. of carbon disulfide, and 20 ml. of methanol was heated at 100 for four days. Unchanged starting materials were removed under reduced pressure. The residue was distilled through a micro column to give 3.0 g. of 4-carbethoxy-2-methoxy- 1,3-dithiole, B.P. 9295 at 0.5 torr, n 1.5656.

Analysis.--Calcd. for C7H10O3S3 (percent): C, 40.75; H, 4.89; S, 31.09. Found (percent): C, 40.86; H, 5.05; S, 31.03.

H NMR: Methyl triplet centered at 6 1.23 [3], methoxyl singlet at 6 3.12 [3], methylene quartet centered at 6 4.18 [2], and methine singlets at 6 6.98 [1] and 7.40 [1].

IR: 3000 (m.), 1700 (s.), 1550 (s.), 1450 (m.), 1390 (w.), 1360) (m.), 1280 (s.), 1250 (s.), 1200 (m.), 1180 (m.), 1090 (m.), 1050 (s.), 1000 (m.), 920 (m.), 900 (s.), 880 (m.), 840 (m.).

UV: In ethanol, A 304 (e 6080) and sh. 230 nm. (-e 4260).

EXAMPLE 5 4,5-bis(carbomethoxy)-2-methoxy1,3-dithiole (Formula 4; R =R =COOCH X=OCH CHaO 0O C-S H A mixture of ml. of carbon disulfide, 15 ml. of methanol, and 14.2 g. of dimethyl acetylenedicarboxylate was heated at 100 for three days. The addition of ether to the contents of the tube precipitated 6.3 g. (25%) of crude 4,- 5 bis(carbomethoxy)-2-methoxy-1,3-dithiole, M.P. 39- 44. Recrystallization from methanol raised the melting point to 60.5-61.5

Analysis.Calcd. for C H O S (percent): C, 38.38; H, 4.03; S, 25.62. Found (percent): C, 38.42; H, 4.18; S, 25.53.

H NMR: Methoxyl singlet at 6 3.30 [3], methoxycarbonyl singlet at 6 3.82 [6], and methine singlet at 6 6.83 [1].

UV: ln methanol, x 314 (e 5120), 238 (e 3780), and 218 nm. (e 3190).

When the reaction was run at 130 for eight hours, a 60% yield was obtained,

8 EXAMPLE 6 4,5 bis(trifiuoromethyl) 2 (4 hydroxyphenyl) 1,3- dithiole (Formula 4; R =R =CF X=4-hydroxyphenyl) GFaC- S\ /II CML K3 F NMR: Singlet at ;+3163 c.p.s. from trichlorofiuoromethane.

H NMR: A singlet at 6 6.22 [1] and an aromatic multiplet [5] which included the hydroxyl hydrogen.

IR: 3330 (m.), 1605 (s.), 1515 (m.), 1500 (m.), 1460 (m.), 1330 (m.), 1270 (s.), 1180 (s.), 1140 (s.), 1090 (m.), 1040 (m.), 920 (s.).

UV: In isooctane, A 325 (e 2590) and 282 nm. (e 3980).

EXAMPLE 7 Dimethyl 2 (2,5 dichloro 4 hydroxyphenyl) 1,3-

dithiole 4,5 dicarboxylate (Formula 4; R =R COOCH X 2,5-dichloro-4-hydroxyphenyl) 01-130 oc-o-s Cl 01130 oc ii-s \OH A mixture of 36 g. of dimethyl acetylenedicarboxylate, 50 g. of 2,5-dichlorophenol, and ml. of carbon disulfide Was heated at for eight hours. Filtration of the reaction product gave 24.3 g. of crude dimethyl 2-(2,5- dichloro-4-hydroxyphenyl)-1,3-dithiole 4,5 dicarboxylate which melted at 134-136". Recrystallization from ethanol raised the melting point to 177-178.

Analysis-Calcd. for C H Cl O S (percent): C, 40.92; H, 2.65; Cl, 18.60; S, 16.82. Found (percent): C, 41.28; H, 2.88; Cl, 18.39; S, 16.89.

H NMR (in hexadeuterioacetone): Methyl [6] singlet at 6 3.23, dithiole hydrogen singlet [1] at 6 5.80, and aromatic hydrogen singlets at 6.60 [1] and 6 7.24 [1]. There was a broad resonance at 6 2.55 [1] for the hydroxy hydrogen. This moved to lower field upon addition of D 0. The absence of coupling between the two aromatic hydrogens indicates that they are para to each other.

IR: 3300 (m.), 2970 (W.), 1740 (s.), 1700 (s.), 1600 (m.), 1580 (s.), 1480 (m.), 1450 m.), 1400 (m.), 1310 (s.), 1270 (s.), 1220 (s.), 1100 (m.), 1080 (s.), 1025 (m.), 970 (m.), 950 (w.), 910 (w.), 885 (w.), 875 (w.), 860 (m.), 830 (w.), 785 (m.), 770 (w.), 760 (m.), 750 (w.), 730 (w.), 700 (m., 690 m.).

UV: In ethanol, k 350 (e 4080) and 286 nm. (e 6400).

9 EXAMPLE 8 2 benzoyl 4,5 bis(trifluoromethyl) 1,3 dithiole and 2 benzoyl 4,4,5,5' tetrakis(trifluoromethyl)- 2,2-di-(1,3-dithiole) S-CCF:

A mixture of 20 ml. of carbon disulfide, 15 g. of benzaldehyde, and 16.5 g. of hexafiuoro-Z-butyne was heated at 100 for six days. The volatiles were removed under reduced pressure, leaving an oily residue. Some solid was obtained by adding hexane. Filtration gave 1.8 g. of pale yellow solid, M.P. 82-86. Recrystallization of part of this solid from hexane gave 2-benzoyl-4,5-bis(trifluoromethyl)-1,3-dithiole, M.P. 87-88.

Analysis.-Calcd. for C H F OS (percent): C, 41.86; H, 1.78; S, 18.62; F, 33.11. Found (percent): C, 41.28; H, 1.75; S, 19.17; F, 34.39.

P NMR showed one peak at +3173 c.p.s. from trichlorofiuoromethane. H NMR showed an aromatic multiplet and a singlet [1] at 6 6.19.

IR: 1690 (s.), 1610 (s.), 1590 (m.), 1450 (m.), 1270 (s.), 1'1'60 (s.), 1080 (m.), 1000 (m.), 990 (m.), 925 (m.), 850 (m.), 820 (m.), 780 (m.), 735 (m.), 720 (m.), 700 (m.), 685 (m.), 660 (m.).

'UV: In isooctane, A 357 (s 743), sh. 310 (e 2000), 249

Part of the filtrate residue from above was chromatographed on a commercial analytical adsorbent (Florisil). Elution with hexane yielded crystalline 2- benzoy1-4,4',5,5'-tetrakis(trifluoromethyl)-2,2' di (1,3- dithiole), M.P. 4345.

Analysis.-Calcd. for C H F OS (percent): C, 35.05; H, 1.04; S, 22.02; F, 39.14 (MW, 582.50). Found (percent): C, 35.20; H, 1.17; 5, 22.01; F, 40.32 (MW, mass spec., m/e 582).

P NMR showed two peaks of equal intensity at {+3161 and +3189 c.p.s. from trichlorofluoromethane.

H NMR showed an aromatic multiplet [5] and a singlet IR (cm:- 1660 (s.), 1610 (s.), 1580 (m.), 1450 (m.), 1270 (s.), 1170 (s.), 1040 (w.), 1020 (w.), 1000 (w.), 975 (w.), 920 (s.), 875 (w.), 840 (m.), 835 (w.), 775 (m.), 760 (m.), 720 (s), 695 (s.), 685 (s.), 660 (w.).

UV: In isooctane, sh. 380 (e 245) sh. 325 (e 2690), 267

Mass spec.: The most abundant ions were at m/e 343 and 239, suggesting predominant cleavage of the central carbon-carbon bond giving the stable dithiolium ions.

Analysis of the crude reaction mixture by NMR (the lines at 6 6.19 and 6 5.52) indicated that the two compounds were formed in a 30:70 ratio, respectively.

10 EXAMPLE 9 2-cinnamoyl-4,4', 5,5 '-tetrakis (trifiuoromethyl) -2, 2- bi-(1,3-dithiole) A mixture containing 16.5 g. of hexafluoro-Z-butyne, 24 g. of carbon disulfide, and 15 g. of cinnamaldehyde was heated at for 3.5 days. The reaction product was concentrated under reduced pressure to remove excess carbon disulfide. Methanol was added to the residue, and it was cooled to -70 to cause crystallization. Filtration gave 10.2 g. of 2-cinnamoyl-4,4-5,5'-tetrakis(trifluoromethyl)-2,2'-di-(1,3-dithiole), which melted at 78- 79". Recrystallization from hexane raised the melting point to 88.

Ana'lysis.-Calcd. for C H F OS (percent): C, 37.50; H, 1.32; S, 21.08; F, 37.47. Found (percent): C, 37.44; H, 1.49; S, 21.20; F, 37.51.

C F C FaC- S OH:

CFs-C A mixture of 15 g. of propionaldehyde, 15 ml. of carbon disulfide, and 16.5 g. of hexafluoro-Z-butyne was heated at 100 for four days. The reaction mixture was distilled under reduced pressure to give 8.1 g. of a-methyl- 4,5-bis(trifluoromethyl)-1,3-dithiole-2-acetaldehyde as a pale-yellow liquid, B.P. 54-55 at 0.25 torr, 12 1.4428.

Analysis.--Calcd. for C H F OS (percent): C, 32.43; H, 2.04; S, 21.65; F, 38.48. Found (percent): C, 32.34; H, 2.04; S, 21.61; F, 40.33.

H NMR: Formyl (CHO) hydrogen [1] as abroadened singlet at 5 9.40, dithiole hydrogen [1] as a doublet (J=6 c.p.s.) at I5 5.03, hydrogen multiplet [1], at 5 2.81 and a methyl [3] doublet (J=7 c.p.s.) at 6 1.24.

IR: Strong absorption at 1720 (carbonyl), 1620 (CC double bond) and 1200 cm." (CF).

EXAMPLE 11 2-acetonyl-4,5-bis(trifiuoromethyl)-1,3-dithiole (Formula 4; R =R =CF X=CH COCH CFaC-S CH-OH C 0 CH3 CF 3 -S A mixture of 15 ml. of acetone, 15 ml. of carbon disulfide, and 17.3 g. of hexafluoro-Z-butyne was heated at 100 for four days. Distillation of the reaction mixture through a small column gave 5.6 g. of 2-acetonyl-4,5- bis- (trifluoromethyl) 1,3-dithio1e, B.P. '6465 at 2.5 torr, 11 1.4441. V

Analysis.Calcd. for C H F OS (percent): C, 32.43; H, 2.04; S, 21.65; F, 38.48. Found (percent): C, 32.67; H, 2.08; S, 21.51; F, 40.28.

H NMR: methyl singlet [3] at 6 1.93, methylene doublet [2] centered at 6 3.03 (i=7 c.p.s.), and methine triplet [1] centered at 6 4.90.

EXAMPLE 12 a,a-Dimethyl-4,5-bis(trifluorornethyl)-1,3-dithiole- Z-acetaldehyde C FaCS CH3 CH-C-CHO A mixture of 15 ml. of carbon disulfide, 15 ml. of isobutyraldehyde, and 16.5 g. of hexafluoro-Z-butyne was heated at 100 for three days. The reaction mixture was distilled through a short still head to give 9.0 g. of product, B.P. 45-50 at 0.6 torr, 21 1.4400.

Analysis.Calcd. for C H F OS (percent): C, 34.84; H, 2.60; S, 20.67; F, 36.74. Found (percent): C, 35.07; H, 2.57; S, 19.85; F, 38.32.

H NMR: Methyl singlet [6] at 6 1.17, methine singlet [1] at 6 5.08, and formyl hydrogen singlet [1] at 6 9.37.

EXAMPLE 13 2 l-methyl-Z-oxopropyl) -4,5-bis (trifluoromethyl 1,3-dithiole CH-CHCOCH CFaC-S A mixture of 15 ml. of carbon disulfide, 15 ml. of methyl ethyl ketone, and 16.5 g. of hexafiuoro-Z-butyne was heated at 100 for four days. Distillation f the reaction mixture gave 9.2 g. of 2-(1-methyl-2-oxopropyl)- 4,5-bis(trifluoromethyl)-1,3-dithiole, B.P. 52-56 at 0.15 torr, n 1.4443.

Analysis.--Calcd. for C H F OS (percent): C, 34.84; H, 2.60; S, 20.67; F, 36.74. Found (percent): C, 34.92; H, 2.51; S, 20.76; F, 38.80.

H NMR: Methyl doublet [3] centered at 6 1.14 (J=7 c.p.s.), methyl singlet [3] at 6 1.95, methine multiplet [1] centered at 6 2.91, and a methine doublet [1] centered at 6 4.90 (1:8 c.p.s.).

EXAMPLE l4 12 H NMR: Methyl singlet [6] at 6 2.33, and the methine hydrogens as an AB pattern [2] (J =11 c.p.s.) around 6 5. IR: Carbonyl at 1700 and double bond at 1600 cmr EXAMPLE 15 2-benzoylmethyl-4,5-bis(trifiuoromethyl)-1,3-dithiole (Formula 4; R =R =CF X=CH COC H A sealed tube containing 12 g. of acetophenone, 15 ml. of carbon disulfide, and 16.7 g. of hexafluoro-Z-butyne was heated at 100 for six days. Filtration of the reaction mixture gave 28.3 g. of 2-benzoylmethyl-4,5-bis(trifiuoromethyl)-1,3-dithiole, M.P. 87. Recrystallization from hexane raised the melting point to 8788.

Analysis.-Calcd. for C H F OS (percent): C, 43.57; H, 2.25; S, 17.89; F, 31.81. Found (percent): C, 43.91; H, 2.40; S, 18.01; F, 32.70.

H NMR: Methylene doublet [2] centered at 6 3.65, methine triplet [1] centered at 6 5.20, and aromatic multiplet [5].

IR: Carbonyl absorption at 1700 cmr EXAMPLE 16 2-(2-oxocyclohexyl) -4,5-bi-s(trifluoromethyl)-1,3-dithiole CF 0 n /CH CF30 A mixture of 15 ml. of cyc'lohexanone, 15 ml. of carbon disulfide, and 17.2 g. of hexafiuoro-Z-butyne was heated at for five days. The product was distilled through a short still head to give 25.2 g. of 2-(2-oxocycl0hexyl)- 4,5-bis(trifluoromethyl)-1,3-dithiole, B.P. 108 at 1.5 torr, n 1.4739.

Analysis.Calcd. for C H F OS (percent): C, 39.28; H, 3.00; S, 19.07; F, 33.90. Found (percent): C, 39.43; H, 3.22; S, 18.76; F, 34.40.

H NMR: Broad absorption at 6 1.0-3.0 [9] and a doublet centered at 6 5.12 [1] with J =6 c.p.s.

EXAMPLE 17 MethyI-Z-diacetylmethyl-1,3-dithiole-4-carboxylate [Formula 4; R =CH CO0- R =H; X=CH(COCH HOS oH-oH ooorr,

A mixture of 21 g. of methyl propiolate, g. of carbon disulfide, and 40 g. of 2,4-pentanedione was heated at for six hours. The mixture was concentrated under reduced pressure to remove unchanged starting materials. The nonvolatile residue was dissolved in methanol and cooled to --78 to cause crystallization. Filtration gave 11.3 g. of crystalline methyl-Z-diacetylmethyl-1,3-dithiole- 4-carboxylate which melted at 113-115 Recrystallization from methanol raised the melting point to 119-120".

Analysis.-Calcd. for C H O S (percent): C, 46.13; H, 4.64; S, 24.64. Found (percent): C, 46.26; H, 4.60; S, 25.07.

H NMR: Acetylmethyl [6] singlet at 6 2.28, methoxyl [3] singlet at 6 3.78, the methine hydrogens [2] as an AB pattern (J=11 c.p.s.) with chemical shifts at 6 13 4.60 and 5.48, and a dithiole hydrogen [1] singlet at 6 7.12.

EXAMPLE 18 2- l-(Z-methoxy-1-trifluoromethylcyclopropyl)trifiuoroethylidene] -4,5-bis (trifluoromethyl -l,3-dithiole (Formula 5; R =CFa; Y and Z together are A mixture containing 18 g. of hexafluoro-Z-butyne, 25.2 g. of carbon disulfide, and 19 g. of methyl vinyl ether was heated at 100 for 3.5 days. The product was distilled under reduced pressure through a spinning-band column. 2-[1-(2 methoxy 1 trifluoromethylcyclopropyl)trifluoroethylene]-4,5-bis(trifluoromethyl) 1,3 dithiole was collected at 85-88 and 3.0 torr in a yield of 17.6 g. The center cut, B.P. 87.5 at 3.0 torr, n 1.4291 (6.74 g.), was analyzed.

Analysis.Calcd. for C H F OS (percent): C, 31.5; H, 1.32; F, 49.8; S, 14.0. Found (percent): C, 32.0; H, 1.58; F, 49.9; S, 14.4.

The H NMR spectrum clearly showed the presence of two stereoisomers, corresponding to the 1,2-disubstitutcd cyclopropyl grup. The cyclopropylmethylene resonance was a series of eight peaks [2] at the relatively high field position of 6 1.0 to 1.6. The methoxyl resonance was two peaks [3] at 6 6.6. The methine hydrogen (intensity 1) resonance occurred as four peaks, each split into a doublet around 6 3.85.

The near-infrared spectrum clearly showed the absorption at 6060 emfcharacteristic of the cyclopropylmethylene group.

EXAMPLE 19 2- 1- (2-ethoxy-1-trifiuoromethylcyclopropyl) trifluoroethylidene] -4,5-bis(trifluoromethyl) -1,3-dithiole CHOCHzCHa (Formula 5; R CFQ; Y and Z together form CFaC-S CF: CF:

0: -CHOCH1CH:

CF S OH;

A mixture containing 16.5 g. of hexafluoro-Z-butyne, 25 .2 g. of carbon disulfide and 14 g. of ethyl vinyl ether was heated at 70 for six days. Volatile liquids were removed under reduced pressure. The residue was filtered to give 0.69 g. of white solid which melted at 52-54. The filtrate was distilled to give 7.12 g. of product which boiled at 5262 and 0.40 torr. The liquid (a mixture of stereoisomers of the dithiole shown above) and the solid (principally one isomer) had nearly identical infrared and NMR spectra. Recrystallization of the solid from hexane raised the melting point to 64-655". This recrystallized solid was analyzed.

Analysis.--Calcd. for C H F OS (percent): C, 33.1; H, 1.71; F, 48.3; S, 13.6 (MW, 472). Found (percent): C, 33.6; H, 1.86; F, 47.4; S, 13.8 (MW, mass spec., 472).

The infrared spectrum showed carbon-carbon doublebond absorption at 1580 cm.- as well as strong CF absorption. The H and P NMR spectra confirmed that the product was a mixture of two stereoisomers. An overlapping pair of -CH--CH and OCH -CH patterns was seen.

14 EXAMPLE 20 (Formula 5; R =CFa; Y and Z together form EXAMPLE 21 2-[2-acetoxy bis 1,2 (trifluoromethyl)ethylidene]- 4,5-bis(trifiuoromethyl) 1,3 dithiole (Formula 5; R =CF Y=H; Z=CH COO) CPS-C cs on coon CFFH 2 a A mixture of 15 ml. of acetic acid, 15 ml. of carbon disulfide, and 17.6 g. of hexafluoro-2-butyne was heated at for three days. After the tube was cooled and opened, a small amount of gas evolved as the contents warmed to room temperature. The tube contents were poured into 250 ml. water. A red liquid separated and was extracted into ether. The ether solution was rinsed with water, dried over magnesium sulfate, and aspirated. The residue partly crystallized and was filtered to give 3.8 g. (16%) of the orange bi-dithiole (B) (described in Example 23, below), M.P. 86-89. The filtrate was concentrated under reduced pressure and the residue was distilled to give 16.9 g. (73%) of 2-[2-acetoxybis-1,2- (trifluoromethyl)ethylideue]-4,5-bis (trifiuoromethyl)- 1,3-dithiole, (A), B.P. 40-48 at 0.3 torr, 11 1.4202.

Analysis.-Calcd. for C H F O S (percent): C, 28.70; H, 0.88; F, 49.54; S, 13.92. Found (percent): C, 28.76; H, 0.82.; F, 49.43; S, 15.12

H NMR: Methyl [3] at 6 1.98 and a hydrogen [1] as a quartet (I-7 c.p.s.) centered at 6 5.73. F NMR calibrated from trichlorofluoromethane showed three areas of resonance: A single peak at +3209 c.p.s. [6], a quartet centered at +3541 c.p.s. [3] and a six-line pattern centered at +4270 c.p.s. [3].

EXAMPLE 22 2-[2-benzoyloxy 1,2 bis(trifluoromethyl)ethylidene]- 4,5-bis(trifluoromethyl) 1,3 dithiole (Formula 5; R =CF Y=H; Z'=C H COO) CFaC-S CF: CF:

I C=(')-CHOCOCH5 013. --s

A mixture of 17 g. of hexafluoro-Z-butyne, 25 ml. of carbon disulfide, 100 ml. of ethyl ether, and 15 g. of benzoic acid was heated at for eight hours. The pale red solution was dissolved in 300 ml. of ether. The solution was extracted with aqueous sodium carbonate solution to remove unchanged benzoic acid, dried over mag- H NMR: Aromatic multiplet [5] at 6 7.3 to 8.2 and a CH quartet [1] centered at 6 6.14 (1:7 c.p.s.).

R NMR: Three areas: A [6] a complex multiplet centered at +3 156 c.p.s. from trichlorofluoromethane; B [3] a quartet centered at +3478 c.p.s., J: c.p.s.; C [3] a quartet split into doublets centered at {+4183 c.p.s., J =10 c.p.s., J =7 c.p.s.

IR: 1650 cm.- (carbonyl), 1600 and 1540 cm.

(C=C), and 1260 and 1180 cm." (CF).

EXAMPLE 23 4,4'-,5,5 '-tetrakis(trif1uoromethyl -A -bi- (1,3-dithiole) (Formula 1; R =R CF o FsC- s s -oo Fa OFBCOOH omozoom cs, o=o ll CFa S S- CFa A mixture of 19 g. of carbon disulfide, 15.6 g. of hexafiuoro-Z-butyne and 23 g. of trifluoroaicetic acid (pK 0.23) was heated at 100 for four days. A little pentane was added, and the mixture was filtered to give 23.2 g. (100%) of the red orange crystalline product, M.P. 88-89".

Analysis.-Calcd. for C F S (percent): C, 25.2; F, 47.9; S, 26.9 (MW, 476). Found (percent): C, 25.5; F, 47.8; S, 27.2 (MW, mass spec., 476).

Mass spec.: In addition to the parent peak there was an abundant peak at m/e 238 (half parent).

UV: In isooctane, A 412 (e 1520), 310 (6 13,600) and 222 nm. (e 12,600).

F NMR: One single sharp peak at --578 c.p.s. from external 1,2-difluorotetrachloromethane.

IR: Strong carbon-carbon double-bond absorption at 1610 cmr Heating the reactants in the absence of the acid gave a low (2%) yield of the above product. In the presence of acetic acid (pK, 4.76; Example 21) the yield of the bi-dithiole was 16%. With formic acid (pK 3.75) the yield was 50%.

EXAMPLE 24 Tetramethyl-A '-'bi-( 1,3-dithiole) -4,4,5 ,5 '-tetracarboxylate (Formula 1; R =R =CH COO) l C=O H cmooo- -s s- 0000113 A mixture of 14.2 g. of dimethyl acetylenedicarboxylate, 25.2 g. of carbon disulfide, and 22 g. of acetic acid was heated at 100 for four days. The mixture was filtered to give 2.1 g. of the bi-dithiole, M.P. 165-168". Recrystallization from benzene-hexane raised the melting point to 169170.

Anulysis.Calcd. for C H 0 S (percent): C, 38.5; H, 2.77; S, 29.4. Found (percent): C, 38.8; H, 2.83; S, 29.3.

The H NMR spectrum of the product showed only one peak, at 6 3.85. The infrared spectrum showed carbonyl absorption at 1710 and 1740 cm." and carboncarbon double bond absorption at 1570 GEL-1. The ultraviolet spectrum (ethanol) showed absorption at 445 (e 1930), 315 (6 13,100), 284 (6 14,300), and 245 um. (e 15,500).

16 EXAMPLE 2s Diethyl A '-bi-(1,3-dithiole)-4,4'-dicarboxylate (A); diethyl A -bi-(1,3-dithiole)-4,5'-dicarboxylate (B) Ether was added to the distillation residue of Example 4, and filtration gave 0.31 g. of the bi-dithiole, which is either one of the two geometric isomers (A) and (B), possibly contaminated with the other isomer. The product melted at 144". Recrystallization from methanol raised the melting point to 169172.

Analysis.Calcd. for C H 0 S (percent): C, 41.3; H, 3.47; S, 36.8. Found (percent): C, 41.3; H, 3.43; S, 37.1.

The H NMR spectrum showed a methyl triplet [3] centered at 6 1.35, a methylene quartet [2] centered at 6 4.31, and a methine singlet [1] at 6 7.40.

EXAMPLE 26 s Tetrathianediylidenedi [bis (trifluoromethyl) ethanediylidene] 2,2'-bis [4,5-bis(trifluoromethyl)-1,3-dithiole] (Formula 2; R =R =CF 100 CFaCECCFa US;

CFaC-S CF; s-CCE;

A mixture containing 16 g. of hexafluoro-Z-butyne and 25.2 g. of carbon disulfide was heated at 100 for 2.5 days. Addition of hexane (60 g.) precipitated a solid. Filtration gave 4.3 g. (20%) of crude s-tetrathianediylidenedi [bis(trifluoromethyl)ethanediylidene] 2,2-bis [4,5-bis(trifluoromethyl)-1,3-dithiole] which melted at 177. Recrystallization from acetone gave white crystals of the product which melted at when immersed in a preheated bath.

Analysis.Calcd. for (1 F 8 (percent): C, 25.2; F, 47.9; S, 26.9 (MW, 932). Found (percent): C, 25.1; F, 48.0; S, 28.0 (MW, 921, ebullioscopic in acetone).

IR: Carbon-carbon double-bond absorption at 1575 cmr Strong CF absorption at 1150 and 1250 cm.- UV: A 288 nm. (6 16,500) in isooctane.

The hexane filtrate from above was concentrated and the residue was refiltered to give 8.15 g. of amorphous solid. The ether-insoluble and hexane-soluble parts were separated from the bulk of the solid (7.05 g., M.P. 105- 112 C.), which was soluble in ether or hexane but insoluble in methanol. A small amount of this material was sublimed, and the sublimate melted at 119-121 C. The infrared spectrum of the sublimate was identical to that of (1,1,1,4,4,4-hexafluoro-2,3-butadiyliene)-2,2 bis[4,5- (trifluoromethyl)1,3-dithiole], described by Krespan and England, J. Org. Chem. 33, 1853-1854 (1968).

When a mixture of 16.8 g. of the hexafluoro-Z-butyne and 50.4 g. of carbon disulfide was similarly heated, a yield of 12.8 g. (60%) of the product of Formula 2 (R =R =CF was obtained.

17 18 EXAMPLE 27 M t Tetramethyl s-tetrath1aned1yl1dened1[b1s(meth0xycarbonmm yl)ethanediylidene]-2,2 bis(1,3-dithiole-4,5-dicarbx- Intenmy Assignment xylate) (Formula 2; R =R =COOCH 6.539 Parent 5 471 P-OCH:

383 P-COOCH: QOOCHa COOCHS 399 P2COOCHI omoooo-s 000cm s-s 000cm 2&5 o= =0 o=os-cooocn, CHSOOC 360 20.1 CH=O0C-CS\ s- 000cm Cmoocs A mixture of 14.2 g. of dimethyl acetylenedicarbox- 289 531-1 ylate and 50.4 g. of carbon disulfide was heated at 100 CHOOC C S COOCH for 18 hours. The mixture was filtered to give 1.11 g. of 16 2 solid tetramethyl s-tetrathianediylidenedi[bis-methoxycarbonyl)ethanediylidene] 2,2 bis(l,3-dithiole-4,5-dicarboxylate) which melted at 237-239 with decomposi- 2 tion. Recrystallization from diethylene glycol dimethyl 0 The H NMR spectrum showed three unsplit methoxyl ether raised the melting point to 247250 with decomgroups of equal intensity at 6 3.92, 3.87, and 3.75. The position. infrared spectrum showed carbonyl absorptions at 1740 Analysis.-Calcd. for C H O S (percent): C, 38.5; and 1720 cm.- and strong absorption at 1580 cm.-' of H, 2.77; S, 29.4. Found (percent): C, 38.9; H, 3.04; S, 25 the carbon-carbon double bond. 29.1. The usefulness of the novel compounds of this invention was demonstrated in the following manner: Solu- IR: carbonyl absorptloln at 1750 9 and 1720 tions of five compounds in acetone were prepared as shown Carbon-carbon doub e-bond absorptlon at 1550 cm. in the following table.

Grams Acetone Solution Compound (example) (ml.)

1 CFr-CS s-C-C F3 0.27 23) 1o ll H CFz- -s S-COF:

CFr-C-S $15: (JFQ /SS\ (TF3 $15: S-C-CF:

C=C--C=C\ /C=C-C==C\ CFr-C-S SS S- CF:

3 CFa-OS CF: CF: s-c-cn 0.08(26) 5 c= l=c OF;- S s- -CF:

4 OFa-C-S 0.1205) 5 CH-CHaCOCtHu CFss 5 CFr-C-S CIFs 01% 0 5 C=C-C\-7CH-OCHI OF;- --S CH:

EXAMPLE 28 Each solution was tested by dipping a cloth into it and Tetramethyl bis(methoxycarbonyl)ethanediylidene 2,2-

bis-(1,3-dithiole-4,S-dicarboxylate) (Formula 3; R =R =COOCH CHaOOCCECCOOCHB CS1 CHsOOC-C-S 000C113 COOCH: S-C COOO S omooo-c-s s-o 000011,

then rubbing a tarnished silverware fork with the wetted area. In each test the wetted cloth removed the tarnish and improved the appearance of the silver. In a similar test with a cloth wetted only with acetone, the tarnished silver remained unchanged in appearance.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the preparation of a compound having the formula R -OS\ /H in which R is a member of the group alkoxycarbonyl of up to 12 carbon atoms, aryloxycarbonyl of up to 13 carbon atoms, lower perfluoroalkyl, arylcarbonyl of up to 13 carbon atoms, or the cyano group;

R is either the same as R or hydrogen, a C -C alkyl, aryl of up to 12 carbon atoms, or aralkyl of up to 12 carbon atoms; and

19 X is selected from the group:

(a) lower alkoxyl (b) or p-hydroxyphenyl substituted with 0-2 groups each of which individually is halogen, lower alkyl, lower alkoxyl, lower alkoxycarbonyl, benzoyl, hydroxyl, the nitro group, or the cyano p;

(c) -CO(CH-=CH),,R in which n is 0 or 1 and R is aryl of up to 12 carbons or aralkyl of up to 12 carbons substituted with hydrogen, lower alkoxyl, lower alkoxycarbonyl, benzoyl, the nitro group, or the cyano group;

s-oru where R, R R and n are as defined above; and

R is hydrogen, lower alkyl, or aryl of up to 12 carbon atoms;

R is hydrogen, lower alkyl, lower alkanoyl, or

aryl of up to 12 carbon atoms;

R is hydrogen, lower alkyl, aryl of up to- 12 carbon atoms, or aralkyl of up to 12 carbon atoms;

with the proviso that R and R taken together can be an alkylene of 2 to 12 carbon atoms;

said process comprising essentially the step of contacting an acetylenic compound having the formula R CECR with carbon disulfide and with the compound HX, at a temperature of about 30-200 C. and at autogeneous pressure each of R R and X having the above-described meaning.

2. The process of claim 1 wherein the temperature is maintained within the range of about 90150 C.

3. The process of claim 2 wherein the starting molar ratios of carbon disulfide to the acetylenic compound and of compound HX to the acetylenic compound do not exceed about 3:1.

4. A compound having the formula R1CS H i R2- S/ \X in which R is a member of the group alkoxycarbonyl of up to 12 carbon atoms, aryloxycarbonyl of up to 13 carbon atoms, lower perfluoroalkyl, arylcarbonyl of up to- 13 carbon atoms, or the cyano group;

R is either the same as R or hydrogen, a C -C alkyl,

aryl of up to 12 carbon atoms, or aralkyl of up to 12 carbon atoms; and

where R R R and n are as defined above; and

where R is hydrogen, lower alkyl, or aryl of up to 12 carbon atoms;

R is hydrogen, lower alkyl, lower alkanoyl, or

aryl of up to 12 carbon atoms;

R is hydrogen, lower alkyl, aryl of up to 12 carbon atoms, or aralkyl of up to 12 carbon atoms;

with the proviso that R and R taken together can be an alkylene of 2 to 12 carbon atoms.

5. The compound of claim 4 named 3-carbomethoxy- 2-methoxy-1,3-dithiole.

References Cited UNITED STATES PATENTS 1/1'964 Mooradian 260243 X OTHER REFERENCES Chemical Abstracts I, vol. 45, col. 2015 (1951).

Chemical Abstracts II, vol. 45, col. 2860 (1951).

Hartzler, J. Am. Chem. Soc., vol. 92, pp. 1412-1414 (Mar. 11, 1970).

Krespan et al., J. Org. Chem., vol. 33, pp. 1850-1854 (1968).

Tomita et al., Chem. Pharm. Bull., vol. 16, pp. 914- 919 and 1324-1329 (1968).

JOHN D. RANDOLPH, Primary Examiner US. Cl. X.R. 

